1. Field of the Invention
This invention relates to an indication device for camera, and more particularly to an indication device for indicating the feeding state of film.
2. Description of the Prior Art
It is known to provide an indication device in which movement of film is sensed to produce a number of pulses, and the viewing condition of an indicator is varied depending on the produced number of pulses, thereby the film feeding state is indicated.
In this type of device, when the film has advanced exactly one frame, the number of pulses produced is made able to reach a prescribed value of, for example, three, and this can be viewed as the indicating pattern varies in synchronism with each of the three pulses.
As the means for sensing the film movement to produce the pulses, use has been made of a mechanical switch with an actuator therefor in frictional contact with the film. If the actuator slips, for example, because of poor frictional force, it will, however, result that despite the normal film feeding operation has taken place, the critical value for the pulse number cannot be reached.
In such a case, as the indicator presents a pattern representing that the film feeding is stopped between frames, the photographer will mistake it as being due to the occurrence of a faulty operation of the film transportation mechanism, despite it having normally operated.
Taking a practical example of the device whose indicating pattern varies in response to production of each of the three pulses from a detecting circuit, beginning with a start position of FIG. 3B and transferring successively to positions of FIGS. 3C to 3E, respectively, as the photographer is accustomed to take the only pattern of FIG. 3E as representing the completion of the film feeding, if it happens by some cause that, despite the film has advanced through the length of one frame, the detecting circuit does not produce three pulses but only two, and therefore, that the indicating operation does not proceed from the position of FIG. 3D, the photographer is given an erroneous information that an abnormal film feeding operation has taken place despite that operation is normal.